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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Remarks:
Internationally accepted method, EPI-Suite, EPA (USA)
Justification for type of information:
See attached the QMRF and QPRF for the QSAR model.


Principles of method if other than guideline:
Calculation by EPI-Suite, EPA (USA) / KOWWIN v1.68
Type of method:
other: estimated by calculation
Partition coefficient type:
octanol-water
Key result
Type:
log Pow
Partition coefficient:
1.69
Remarks on result:
other: (KOWWIN v1.67 estimate. No data is provided on temperature and pH).
Conclusions:
The estimated log octanol-water partition coefficient (Log Kow) is 1.69 (EPI-Suite, KOWWIN v1.68)

Executive summary:

The substance estimated log octanol-water partition coefficient (Log Kow) is 1.69 (EPI-Suite, KOWWIN v1.68)

Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Remarks:
Internationally accepted method, EPI-Suite, EPA (USA)
Justification for type of information:
See attached the QMRF and QPRF for the QSAR model.


Principles of method if other than guideline:
Calculation by EPI-Suite, EPA (USA) / KOWWIN v1.68
Type of method:
other: estimated by calculation
Partition coefficient type:
octanol-water
Key result
Type:
log Pow
Partition coefficient:
-2.01
Remarks on result:
other: (KOWWIN v1.67 estimate. No data is provided on temperature and pH).
Conclusions:
The estimated log octanol-water partition coefficient (Log Kow) is -2.01 (EPI-Suite, KOWWIN v1.68)

Executive summary:

The substance estimated log octanol-water partition coefficient (Log Kow) is -2.01 (EPI-Suite, KOWWIN v1.68)

Endpoint:
partition coefficient
Data waiving:
study technically not feasible
Justification for data waiving:
other:
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
According to Column 2 of REACH Annex VII, the study cannot be conducted since the substance undergoes rapid hydrolysis (half-life < 1h) in aqueous to 2-butanone oxime and the corresponding vinylsilanetriol. Moreover, silanetriols undergo continuous condensation reactions to produce higher molecular weight siloxanes which are considered biologically unavailable.
Endpoint:
partition coefficient
Type of information:
other: Handbook peer reviewed
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Principles of method if other than guideline:
No data provided on the method.
GLP compliance:
not specified
Type of method:
other: no data
Key result
Type:
log Pow
Partition coefficient:
0.36
Remarks on result:
other: (temperature and pH were not indicated)
Conclusions:
The partition coefficient (log Pow) of butanone oxime is 0.36.
Executive summary:

The partition coefficient (log Pow) of butanone oxime is 0.36.

Description of key information

The Log Kow of test item should be understood based on its degradation products since it undergoes rapid hydrolysis (half-life < 1h) in aqueous to 2-butanone oxime (log Kow = 1.69, KOWWIN v1.68) and vinylsilanetriol (Log Kow = -2.01, KOWWIN v1.68).

Key value for chemical safety assessment

Log Kow (Log Pow):
1.69

Additional information

According to Column 2 of REACH Annex VII, the study cannot be conducted since the substance undergoes rapid hydrolysis (half-life < 1h) in aqueous to 2-butanone oxime and vinylsilanetriol. Morevoer, the corresponding silanols undergo continuous condensation reactions to produce higher molecular weight siloxanes which are considered biologically unavailable.

The estimated log octanol-water partition coefficients (Log Kow) for the degradation products, 2 -butanone oxime and vinylsilanetriol were 1.69 and -2.01 (EPI-Suite, KOWWIN v1.68). Moreover, according to Verschueren et al (2009) the Log Kow of 2 -butanone oxime was reported to be 0.36.